Method of and apparatus for producing articles having high magnetic permeability from billets of temporarily magnetizable (i.e., soft magnetic) material

ABSTRACT

A billet of temporarily magnetizable (i.e., soft magnetic) material is deformed by a controlled flow of pressurized extrusion fluid passing between the nose of the billet and a flow control surface, thereby to give the product a preferred texture and crystallographic orientation. Heat generated in the material as a result of the deformation is employed to elevate the temperature of the material to magnetic annealing temperature, supplemented by auxiliary heating means if the heat of deformation is insufficient, or by cooling means if the heat of deformation is excessive, and the deformed material is magnetically annealed in a magnetizing field downstream from the exit end of the zone of deformation. The billet may be round or rectangular, of finite or of indefinite length, and the product may be wire or strip or sheet having high magnetic permeability.

United States Patent Oldis et al.

[ 51 Dec. 30, 1975 [5 METHOD OF AND APPARATUS FOR 1,978,220 10 1934 Otte 148 108 PRODUCING ARTICLES HAVING HIGH 32??? 2 823 g 5 l But an eta 14 I108 z tfi g PERMEABILITY FROM 3,l 18,795 l/l964 Kolbe et al. 29/5275 3 OF TEMPORARILY 3,417,589 12/1968 Bobrowsky' 72/60 MAGNETIZABLE (l.E., SOFT MAGNETIC) 3,677,048 7/1972 Fuchs, Jr. 72/60 MATERIAL Primar Examiner-Milton S. Mehr 75 Inventors: 0hn Edw d Old C I I y l z gf z nd Attorney, Agent, or Firm-D. P. Kelley; A. S. Rosen Venkatesan, Princeton, NJ. [73 A I w El [57] ABSTRACT I Sslgnee' j g 3? Company A billet of temporarily magnetizable (i.e., soft magnetic) material is deformed by a controlled flow of [22] Filed: Jan. 27, 1975 pressurized extrusion fluid passing between the nose f the billet and a flow control surface thereb to ive 2 o y g l H App] No 544527 the product a preferred texture and crystallographic Related US. Application Data orientation. Heat generated in the material as a result [62] Division f 423,948 27 1973, of the deformation is employed to elevate the temperabandoned. ature of the material to magnetic annealing temperature, supplemented by auxiliary heating means if the 152 11.5. c1. 72/60; 148/108; 72 342; heat of deformation is insufficient, or y cooling 72/257 means if the heat of deformation is excessive, and the {511 1m. c1. B21G 23/00 deformed material is magnetically annealed in a [58] Field of Search 72/60, 253, 272, 257; notlzlng field downstream m the exit end of the 143/10 1 10 zone of deformation. The billet may be round or rectangular, of finite or of indefinite length, and the prodl References Cited uct may be wire or strip or sheet having high magnetic UNITED STATES PATENTS pelmeabllly- 1,978,219 10/1934 Otte 148/108 6 Claims, 8 Drawlllg Figures o.c. CURRENT 2 2 19 29 a l l l I" 'Al'l 25-: fl V30 US. Patent Dec.30, 1975 Sheet1of4 3,928,995

D. C. CURRENT US. Patent Dec.30, 1975 Sheet 3 of4 3,928,995

U.S. Patent Dec. 30, 1975 Sheet 4 of 4 METHOD OF AND APPARATUS FOR PRODUCING ARTICLES HAVING HIGH MAGNETIC PERMEABILITY FROM BILLETS OF TEMPOR'ARILY MAGNETIZABLE, (I .E., SOFT MAGNETIC) MATERIAL? A This is a division ofapplication SCI. No. 428,948 filed Dec. 27, I973, now abandoned. 1

BACKGROUND OF THE INVENTION l 1. Field of the Invention This invention relates, broadly speaking, to apparatus and method for the production of articles having; high magnetic permeability. More specifically, this invention relates to the deformation ofa billet of temporarily magnetizable (i.e., soft magnetic) material followed by application to the deformed billet of a magnetic field to produce an article (e.g., wire or strip or sheet) having high magnetic permeability.

2. Description of the Prior Art It is known that the magnetic permeability of temporarily magnetizable (i.e., soft magnetic) materiahand thus the degree to which the material may be magnetized by application thereto of a magnetic field of given strength, is a function of, among other things, the crystallographic orientation of the material. In this respect, the reader's attention is directed to Wire Journal, September 1971, pages 121-124. When the crystallographic orientation of a material provides improved magnetic permeability permitting greater magnetization with a given field strength, the material is said to have a preferred orientation or texture (as distinguishcd from random orientation or texture). Obviously, preferred orientation or texture is desirable in temporarily magnetizable (i.e., soft magnetic) materials useful for transformer cores, reed switches and the like and which are to be magnetized with low coercive force. i

It is also known that the magnetic permeability of temporarily magnetizable (i.e., soft magnetic) materials is improved by annealing the material in a magnetic field starting at an annealing temperature well above ambient temperature but below a critical temperature.

Heretofore, wire for magnetic purposes has been produced from a billet of temporarily magnetizable (i.e., soft magnetic) material by deforming the billet in a die to produce the wire and then collecting the wire in coils, any elevation in temperature of the billet material resulting from the work of deformation being-reduced, even to ambient temperature, by'dissipation and wastage of heat from the coiled wire before application thereto of a magnetic field. In such conventional procedure, the deforming operation in the die induces a preferred orientation within the body of the wire,-but the frictional restraint exercised by the die on the surface of the material passing therethrough promotes a random orientation at and adjacent the surface of the wire. Thereafter, in the conventional procedure, the cooled wire is uncoiled, heated to annealing temperature, and is magnetically annealed by being subjected to a magnetic field and allowed to recool in the magnetic field, whereby to produce wire with improved magnetic permeability.

U.S. Pat. No. 1,909,887 (1933') to Otte discloses method and apparatus for the production of magnetic sheet or forgings in which the billet material is heated from ambient temperature to an elevated temperature.

Thereafter, the heated billet material is rolled or forged in a magnetic field and is allowed to cool in the magnetic field. No consideration is given to the restraining effect of the deforming operation on the surface of the material being deformed which restraining effect promotes random crystallographic orientation at and adjacent the surface of the material as hercinbefore described. The patent states that the method is applicable to wire, but does not otherwise disclose how this is to be done.

' SUMMARY OF THE INVENTION ification and by reference to the accompanying drawings and the appended claims. 4

Briefly, we have discovered that the foregoing objects may be attained by deforming a billet of temporarily magneti'zable (i.e., soft magnetic) material by means of a fluid medium to eliminate frictional restraint at the surface of the billet material, the temperature of said deformed billet material rising due to the work of deformation to a temperature which may be the magnetic annealing temperature for such material, or which may require adjustment to said magnetic annealing temperature, subjecting the heated deformed billet material to a magneticfield, and magnetically annealing the deformed billet material by allowingthe said deformed billet material to cool in the magnetic field to ambient or approximately ambient temperature.

BRIEF DESCRIPTION OF-THE DRAWINGS Referring now to the drawings, in which like numerals represent like parts in the several views:

FIG. 1 represents a medial longitudinal section of the present invention, showing, among other things, heating coils inserted in the apparatus;

FIG. 2 represents a section taken along the line 2--Z of FIG. 1;

FIG. 3 represents an enlarged medial longitudinal section of a cooling element positioned in a recess in the fluid control element;

FIG. 4 represents an enlarged medial longitudinal sectionof a conventional die with a billet being extruded therethrough, showing schematically the region of random crystallographic orientation between the billet surface and the phantom lines;

FIG. 5 represents an enlarged longitudinal section of a fluid control element with a billet being extruded therethrough by a controlled pressurized flow of extrusion fluid in the direction indicated by the arrows;

FIG. 6 represents a partially sectional fragmentary view in perspective of apparatus for extruding a rectangular billet of material to produce sheet stock having high magnetic permeability;

FIG. 7 represents a fragmentary view in elevation of the exit end of the apparatus of FIG. 6;

FIG. 8 represents a view in section taken along the line 88 of FIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Extrusion apparatus 1 shown in FIG. 1 is designed to produce wire 2 having high magnetic permeability from a billet 3 of temporarily magnetizable (i.e., soft magnetic) material of finite length, and is an improvement over the apparatus and method disclosed in U.S. Pat. No. 3,677,048 (1972) to Fuchs. The material may, for example, be an alloy selected from the class of ironnickel alloys such as the material known in the industry as PERMALLOY.

Extrusion apparatus 1 comprises pressure vessel 4 having an'inner bore 5 of circular transverse cross-section and which is closed at one end 6. The closed end 6 of pressure vessel 4 may be rigidly mounted on a base 7 by suitable means not shown but known to those familiar with this art.

Ram 8, having a circular transverse cross-section, is adapted to be positioned within and telescopically received by inner bore 5, and is advanced into and retracted out of pressure vessel 4 through the open end thereof by suitable means such as a press or the like (not shown, but known to those familiar with this art).

Fluid control element 9, having a circular transverse cross-section is threadedly mounted in threaded counterbore 10 in the lower end of ram 8, and is provided with a generally upwardly convergent flow control surface 11 having a circular transverse cross-section symmetrical about the longitudinal axis of pressure vessel 4, fluid control element 9 and ram 8.

Fluid control element 9 cooperates with inner bore 5 to define a fluid chamber 12 within which said billet 3 is positioned for extrusion as hereinafter described.

The upper end of fluid control element 9 is provided with an annular recess 13, and the lower end of ram 8 is provided with a complementary annular recess 14. A cylindrical'member 15, provided with a longitudinally extending central bore 16, is mounted within recesses 13 and 14. Embedded within cylindrical member 15 is a magnetizing coil 17. Advantageously, cylindrical member 15 is formed from electrically insulating nonmagnetic material having a high compressive strength to withstand pressures developed in apparatus 1 during the course of operation. Cylindrical member 15 may be formed by compacting sinterable non-metallic electrically insulating powders around magnetizing coil 17 and then sintering the said powders, it being understood that the sintering temperature should not be so high as to damage magnetizing coil 17. That material known in the industry and sold under the trademark LAVITE is suitable for forming cylindrical member 15. Yet other means and methods for providing a non-magnetic electrically insulating cylindrical member 15 in which a magnetizing coil 17 is embedded will be evident to those familiar with the art. For example, cylindrical member 15 may be formed initially in two halves, each half being provided with grooves adapted to receive half the magnetizing coil 17, the two halves of cylindrical member 15 subsequently being assembled and joined around the magnetizing coil 17.

Flow control surface 11 of fluid control element 9 communicates with central bore 16 of cylindrical member 15 to define therewith a passage 18 annularly disposed about the nose of billet 3 and wire 2 immediately adjacent the said nose, said passage 18 communicating between fluid chamber 12 and central bore 19 extend- 4 ing axially throughout the length of ram 8. Central bores 16 and 19 register, as shown.

The outer surface of fluid control element 9 is circuml'crentially recessed at 20, the said recess 20 cooperating with the end of ram 8 to define an annular channel or seat for receiving high pressure seal 21 slidably and sealingly engaging inner bore 5. Advantageously, high pressure seal 21 may include, as shown, an annular cup-shaped soft seal 22 and an annular beryllium-copper anti-extrusion ring 23. It will, of course, be understood that, in lieu of the specific seal structure shown in FIG. 1, other high pressure seals known in the art and suitable for use in providing a sliding seal between adjacent relatively movable surfaces may be employed.

That portion of passage 18 bounded by flow control surface 11 defines a zone of deformation 24 within which deformation of billet 3 occurs during extrusion thereof from apparatus 1.

Ram 8 is provided with passageways 25 through which insulated leads 26 from magnetizing coil 17 extend to communicate with a source of direct current for energizing the said magnetizing coil 17.

Magnetic annealing of a temporarily magnetizable (i.e., soft magnetic) material to increase its magnetic permeability is commenced from a temperature somewhat above ambient temperature but yet below a criti cal temperature which is a characteristic of the specific material. It is known that, in extruding a billet of material, the temperature of the material in the zone of deformation of the extrusion agency increases, and this increase in temperature is related to, among other things, the degree of reduction of the cross-sectional area of the billet. Under some circumstances, the heat generated by the reduction of the billet in the zone of deformation may be sufficient to elevate the temperature of the extruded material to optimum magnetic annealing temperature. Under other circumstances, the heat generated by the reduction of the billet in the zone of deformation may be insufficient. In this event, electrical heating elements 27 may be inserted into recesses 28 in the upper end of fluid control element 9, the said recesses 28 being radially spaced around the cylindrical member 15. Insulated leads 29 extending through passageways 30 in ram 8 communicate between said heating elements 27 and a source (not shown) of electrical current.

On the other hand, heat generated by the reduction of the billet in the zone of deformation may be so great as to raise the temperature of the material above its critical temperature. In this event, cooling elements 31 as shown in FIG. 3 may be inserted in recesses 28, conduits 32 extending through passageways 30 and communicating between said cooling elements 31 and a source (not shown) of coolant.

It will be evident to those familiar with the art that, whether heating elements 27 or cooling elements 31 are employed, thermostatic control means (not shown) responsive to the temperature of the billet material in, or exiting, the zone of deformation 24 may be employed to regulate the degree of heating or cooling as required.

The operation of the embodiment of FIG. 1 will now be described.

In starting up, chamber 12 is filled with a suitable extrusion fluid which may, for example, be castor oil. Billet 3, the head end of which may be preshaped for positioning in the zone of deformation 24, is placed in chamber 12. Ram 8 and fluid control element 9 are then continuously advanced, under the influence of a ram press (not shown, but indicated diagrammatically in FIG. 1 by arrows at the top of the figure), into bore 5 of pressure vessel 4 to establish a positive controlled flow of pressurized extrusion fluid through passage 18, in the manner taught in U.S. Pat. No. 3,677,048 (I972) to Fuchs, whereupon billet 3 is extruded through the zone of deformation 24 to produce wire 2 which exits the zone of deformation 24 and apparatus 1 through bores 16 and 19. It will be noted that the billet material is not in contact with flow control surface 11 of fluid control element 9 at any time during extrusion. Rather, according to the teachings of U.S. Pat. No. 3,677,048 (I972) to Fuchs, to which reference should be made for details, the pressurized extrusion fluid flowing through passage 18 maintains the surface of the billet material spaced from the flow control surface 11 at all times during extrusion, thereby eliminating metal-tomctal contact in the zone of deformation 24 and the frictional restraints inherent in such metal-to-metal contact. Further, according to the teachings of the said U.S. Pat. No. 3,677,048, the flowing pressurized extrusion fluid, in addition to eliminating contact friction between the material of billet 3 and flow control surface 11 in the zone of deformation 24, functions as a deforming agency to deform the material of billet 3 and produce wire 2.

Magnetizing coil 17 has, during the foregoing, been energized through leads 26 by a source of direct current, thereby to establish a magnetizing field. Wire 2 in passing through this magnetizing field is magnetically annealed therein.

As hereinbefore mentioned, for many materials there is an optimum temperature between ambient temperature and an elevated critical temperature from which magnetic annealing is most efficiently commenced, and the heat generated during the reduction of billet 3 may raise the temperature of the extruded material to such optimum temperature. If, for a particular degree of reduction of a particular material, such heat would be insufficient, then auxiliary electrical heating elements 27 may be employed as hereinafter described. On the other hand, if, for a particular degree of reduction of a particular material, the heat of reduction would be excessive, then cooling elements 31 may be employed as hereinbefore described. In any event, the present invention contemplates that wire 2 as it exits the zone of deformation 24 and simultaneously enters bore 16 passing through magnetizing coil 17 will be substantially at the optimum temperature for commencement of magnetic annealing. It is further contemplated that, at some point in bore 16 downstream of the exit end of the zone of deformation 24 (and the electrical heating elements 27 or cooling elements 31 if employed), the wire 2 will commence to cool and be magnetically annealed while in the magnetic field set up by magnetizing coil 17, and will reach ambient temperature or a temperature not significantly above ambient temperature at, or before, the downstream end of bore 16 and the downstream end of the magnetic field set up by magnetizing coil 17. Thus, the length of magnetizing coil 17 and cylindrical member as shown in FIG. 1 is diagrammatic only, and may be shorter or longer relative to the size of the other elements of apparatus 1 as required. The wire 2 passes through bore 19 of ram 8 and is collected at the other end (not shown) of ram 8. At the conclusion of the stroke of ram 8 into pres- 6 sure vessel 4, the said ram 8 and fluid control element 9 may be retracted entirely out of pressure vessel 4 and the said pressure vessel 4 may then be reloaded for another extrusion cycle.

Reference is now made to FIGS. 4 and 5 to illustrate, diagrammatically, differences in surface texture and surface and subsurface crystallographic orientation resulting from extrusion of a billet through a conven tional die and through the fluid control element disclosed in U.S. Pat. No. 3,677,048.

In conventional extrusion, as shown in FIG. 4, a frietional restraint is exerted along the surface of the material being extruded through'a die which is in metaltometal contact with the material. This frictional restraint exists to some degree even if an ordinary film of lubricant is applied to the surface of the material. The frictional restraint along the surface of the material promotes a random crystallographic orientation at the surface of the material, which random cystallographic orientation extends to some depth below the surface of the material asindicated diagrammatically by phantom line 33, even though the bulk of the material may have a preferred crystallographic orientation after extrusion, and the said random crystallographic orientation persists at and near the surface of the wire product. Assuming that a wire of high magnetic permeability is to be produced, and that the billet being extruded through the conventional die consists of temporarilymagnetizable (i.e., soft magnetic) material, it will be apparent that random crystallographic orientation at and near the surface of the wire will adversely affect the magnetic permeability of the wire.

In the extrusion process taught by U.S. Pat. No. 3,677,048 and shown diagrammatically in FIG. 5, a controlled flow of pressurized extrusion fluid is passed, in the direction indicated by the arrows, between a flow control surface of a fluid control element and the nose or head end ofa billet of material being extruded by the action of said controlled flow of pressurized extrusion fluid. There is no frictional, restraint along the surface of the material and consequently there is no, or substantially no, random crystallographic orientation at or near the surface of the material and the wire product, unlike the example of FIG. 4. Assuming that a wire of high magnetic permeability is to be produced, and that the billet being extruded by the controlled flow of pressurized fluid consists of temporarily magnetizable (i.e., soft magnetic) material, it will be apparent that, due to the absence of random crystallographic orientation at and near the surface of the wire, the magnetic permeability of the wire will be greater than that attainable in FIG. 4.

As hereinbefore mentioned, the efficiency of the present magnetic annealing process is greater than that of conventional processes because, in the present process the heat of deformation is utilized in whole or in part to elevate the temperature of the material being magnetically annealed to an optimum temperature for the commencement of magnetic annealing, unlike conventional processes wherein the heat of deformation is dissipated or wasted, thus requiring a reheating step prior to magnetically annealingthc material.

The present invention makes no claim to the discovery of extrusion by means of a controlled flow of pressurized extrusion fluid, for this has already been taught by U.S. Pat. No. 3,677,048 The present invention, however, is broadly based upon the recognition that product such as, but not limited to, wire resulting from the extrusion of a billet of material by means of a controlled flow of pressurized extrusion fluid passing between the nose of the billet and a flow control surface, according to the teachings of US. Pat. No. 3,677,048, has a preferred surface of the product, and that this preferred texture and crystallographic orientation can, together with heat resulting from the extrusion operation, be employed to advantage in producing a product having high magnetic permeability by subjecting a billet of temporarily magnetizable (i.e., soft magnetic) material to such controlled flow of pressurized extrusion fluid and by annealing the deformation-heated product of extrusion in a magnetizing field.

The present invention is not restricted to the specific apparatus shown in FIG. 1, but rather may also employ other types of extrusion apparatus, including apparatus with a fixed control element as well as apparatus adapted for the continuous or cyclic extrusion of billets of temporarily magnetizable (i.e., soft magnetic) material of indefinite or unlimited length, which other apparatus is now known to those familiar with this art, so long as the billet is extruded by a controlled flow of pressurized extrusion fluid passing between the nose of the billet and a flow control surface. It will, of course, be understood that with a fixed fluid control element, means will be provided to advance the billet toward the said fixed fluid control element.

In the embodiment of FIGS. 6, 7 and 8, extrusion apparatus 35 is seen as comprising pressure vessel 36 (the front end of which is shown, and diagrammatically only) in which is mounted rectangular fluid control element 37 having upper and lower flow control surfaces 38 and side flow control surfaces 39 (one of which is shown in FIG. 8). Fluid control element 37 is provided with rectangular recess 40 receiving member 41 having rectangular bore 42, and pressure vessel 36 is provided with rectangular bore 43 registering with bore 42.

Member 41 is constructed from the same class of materials mentioned for cylindrical member of the embodiment of FIG. 1, and has embedded therein rectangular magnetizing coil 44 provided with leads 45 communicating in a suitable manner with a source of direct current (not shown).

Spaced about member 41 is a plurality of recesses 46 which may receive heating or cooling elements corresponding respectively with electrical heating element 17 or cooling elements 31 as shown in FIGS. 1 and 3 for the purposes hereinbefore mentioned in respect to said electrical heating elements 17 and cooling elements 31. FIG. 6 shows electrical heating elements 47 inserted in recesses 46 and connected by means of finsulated leads 48 extending through suitable passageways in pressure vessel 36 to communicate with a source of current (not shown).

A rectangular billet 49 of temporarily magnetizable (i.e., soft magnetic) material, the head end of which is preshaped for positioning in the zone of deformation 50 (FIG. 8) of fluid control element 37, is positioned in pressure vessel 36, with its head end within the said zone of deformation 50, and a controlled flow of pressurized extrusion fluid is provided in the direction indicated by the arrows through the passageways 51 to extrude the billet through bores 42 and 43 and produce sheet product 52, in the manner taught in US. Pat. No. 3,677,048, it being understood that means are provided to continuously advance billet 49 towards fluid control element 37 during the course of the extrusion operation. During the foregoing, magnetizing coil 44 has been energized through leads 45 (FIG. 7) by a source of direct current, thereby to establish a magnetizing field. Sheet product 52, in passing through this magnetizing field, is magnetically annealed therein. Member 41, with magnetizing coil 44 embedded therein, may be extended downstream of bores 42 and 43, if necessary and as indicated in FIG. 8 by dotted lines, to insure that a magnetizing field is applied to sheet product 52 until the temperature of said sheet product 52 falls to ambient temperature or to a temperature not significantly above ambient temperature, whereby to effect magnetic annealing of said sheet product 52.

What is claimed is:

1. Apparatus for producing an article having high magnetic permeability from a billet of temporarily magnetizable material, said apparatus comprising:

a. a fluid control element having a flow control surface providing a zone of deformation having an entrance end adapted to receive the head end of a billet of temporarily magnetizable material and an exit end downstream from said entrance end adapted to discharge deformed material having the cross-section of the desired article,

b. first means to establish a controlled flow of pressurized extrusion fluid through the fluid control element between the flow control surface and the head end of the billet from the entrance end to the exit end of the zone of deformation to deform said billet, I

0. second means to advance said billet into the entrance end of said zone of deformation,

d. a magnetizing coil embedded in said fluid control element and extending from the exit end of the zone of deformation to a station downstream from said exit end and adapted to surround deformed material exiting the exit end of the zone of deformation,

e. a source of direct current connected to said magnetizing coil to energize said magnetizing coil.

2. Apparatus as in claim 1, wherein:

f. the distance between the exit end of the zone of deformation and said station is sufficient to permit deformed material to cool in said magnetizing field from magnetic annealing temperature to approximately ambient temperature.

3. Apparatus as in claim 1, further comprising:

f. third means to adjust the temperature of the deformed material to magnetic annealing temperature.

4. Apparatus as in claim 1, further comprising:

f. third means to adjust the temperature of the deformed material to magnetic annealing temperature, and wherein:

g. the distance between said third means and said station is sufficient to permit deformed material to cool in said magnetizing field from magnetic annealing temperature to approximately ambient temperature.

5. Apparatus as in claim 1, wherein:

f. the exit end of the zone of deformation has a rectangular cross-section.

6. Apparatus as in claim 5, wherein:

g. the entrance end of the zone of deformation has a rectangular cross-section. 

1. Apparatus for producing an article having high magnetic permeability from a billet of temporarily magnetizable material, said apparatus comprising: a. a fluid control element having a flow control surface providing a zone of deformation having an entrance end adapted to receive the head end of a billet of temporarily magnetizable material and an exit end downstream from said entrance end adapted to discharge deformed material having the cross-section of the desired article, b. first means to establish a controlled flow of pressurized extrusion fluid through the fluid control element between the flow control surface and the head end of the billet from the entrance end to the exit end of the zone of deformation to deform said billet, c. second means to advance said billet into the entrance end of said zone of deformation, d. a magnetizing coil embedded in said fluid control element and extending from the exit end of the zone of deformation to a station downstream from said exit end and adapted to surround deformed material exiting the exit end of the zone of deformation, e. a source of direct current connected to said magnetizing coil to energize said magnetizing coil.
 2. Apparatus as in claim 1, wherein: f. the distance between the exit end of the zone of deformation and said station is sufficient to permit deformed material to cool in said magnetizing field from magnetic annealing temperature to approximately ambient temperature.
 3. Apparatus as in claim 1, further comprising: f. third means to adjust the temperature of the deformed material to magnetic annealing temperature.
 4. Apparatus as in claim 1, further comprising: f. third means to adjust the temperature of the deformed material to magnetic annealing temperature, and wherein: g. the distance between said third means and said station is sufficient to permit deformed material to cool in said magnetizing field from magnetic annealing temperature to approximately ambient temperature.
 5. Apparatus as in claim 1, wherein: f. the exit end of the zone of deformation has a rectangular cross-section.
 6. Apparatus as in claim 5, wherein: g. the entrance end of the zone of deformation has a rectangular cross-section. 